[Ginkgo biloba Ketone Ester Tablets with different release rates prepared by fused deposition modeling 3D printing technology].

The present study prepared a new type of Ginkgo biloba ketone ester(GBE50) preparation from polyethylene glycol and croscarmellose sodium with good biocompatibility and a certain viscosity by fused deposition modeling(FDM)-type 3D printing technique. Firstly, a cylindrical 3D printing model with a diameter of 9.00 mm and a height of 4.50 mm was established. Subsequently, the 3D-GBE50 preparations with three paths(concentric, zigzag, and grid), different layer heights, and different filling gaps were designed and prepared after the optimization of the proportions of excipients. The morphology, size, chemical properties, and dissolution activity of the 3D-GBE50 preparations were fully characterized and investigated. The results showed that 3D-GBE50 preparations had smooth appearance, clear texture, standard friability, good thermal stability, and stable chemical properties. Moreover, the printing path, layer height, and filling gap were directly related to the release rate of 3D-GBE50 preparations. The dissolution of 3D-GBE50 tablets with zigzag printing path was the fastest, while the dissolution rates of 3D-GBE50 tablets with concentric circle and grid-shaped printing paths were slower than that of commercially available G. biloba Ketone Ester Tablets. In addition, the dissolution of 3D-GBE50 tablets was faster with higher layer height and wider filling gap. As revealed by the results, th FDM-type 3D printing technique can flexibly regulate the drug release activity via controlling the printing parameters, providing effective ideas and methods for the pre-paration of personalized pharmaceutical preparations.

[Cloning and expression of SmDXS2 gene in Swertia mussotii].

1-deoxy-D-xylulose-5-phosphate synthase2(DXS2) is the first key enzyme of the MEP pathway,which plays an important role in terpene biosynthesis of plants. According to the data of Swertia mussotii transcriptome, DXS2 gene(Gen Bank number MH535905) was cloned and named as Sm DXS2. The bioinformatics results showed that Sm DXS2 has no intron,with a 2 145 bp open reading frame encoding a polypeptide of 714 amino acids. They are belonging to 20 kinds of amino acids,and the most abundant amino acids include Ala,Gly and Trp. The predicted protein molecular weight was 76. 91 k Da and its theoretical isoelectric point(p I) was6. 5,which belonging to a hydrophilic protein. α-Helix and loop were the major motifs of predicted secondary structure of DXS2. The three function domains are TPP＿superfamily,Transket＿pyr＿ superfamily and Transketolase＿C superfamily,respectively. The Sm DXS2 protein shared high identity with other DXS2 proteins of plants. Phylogenetic analysis showed that Sm DXS2 protein is grouped with the gentian DXS2 protein. The recombinant protein of Sm DXS2 gene in Escherichia coli was approximately 92. 00 k Da(containing sumo-His tag protein 13 k Da),which was consistent with the anticipated size.This work will provide a foundation for further functional research of Sm DXS2 protein and increasing the product of iridoid compound by genetic engineering in S. mussotii.